Here are some pictures of the Rumford fireplace that my son (and I) built. Neither of us has ever built a fireplace and we are very much amateur masons. The first stage was built with concrete blocks and the rest we formed and poured out of concrete. The fireplace works great and is a marvel to all who see it.

My only worry is that I don't see any air space or insulation around the lining materials - firebox, throat, smoke chamber and flues - as required by code to give them a little room to expand when hot. See how we used the ceramic fiber paper to wrap the components as described at http://www.rumford.com/concrete.html especially some of the pictures at http://www.rumford.com/KonosuConst.html

If you didn't leave any room for thermal expansion the block and concrete enclosure might crack. That may not be a problem if you plan to veneer or plaster the chimney - just leave your air space or bond break between the structure you have and the veneer.

Even if you consider the concrete finished, if it cracks, you may be able to fill the cracks when hot which may allow the liners to pull away from the enclosure and create the bond break you need.

Let me know if it cracks. It may not but, if it does, I am very interested in "fixes".

Best,
Jim Buckley

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2/1/08
Jim,

Yes, the concrete developed a few hairline cracks after the first few firings. We have kept an eye on them and they do expand and contract slightly as effected by temp. changes. The cracks have not gotten any worse, no new ones have developed and I feel that they were really a blessing in disguise as I believe they allowed the flues some "breathing room." The fireplace works great and I tell everyone I meet about the Rumford. I have a link to your site on my web site as well.

We are planning on building another one at my house in the future and would like to promote and build some more in this area. We live in Chester, SC.